The present invention provides certain improvements in microelectronic component testing. More particularly, the present invention provides probes and probe cards of the type which may be used in testing microelectronic components (e.g., microelectronic components on semiconductor wafers prior to singulation, individual integrated circuit dies, or packaged components). These probes and probe cards are not limited to microelectronic component testing, though, and have utility in a variety of other testing applications, as well.
The microelectronics industry is highly competitive and most microelectronics manufacturers are highly sensitive to quality and cost considerations. Most microelectronics manufacturers require that suppliers of microelectronic components test performance of each microelectronic component before shipment to minimize the manufacturer's product loses. Microelectronics are commonly tested by establishing temporary electrical connections between a test system and electrical contacts on the microelectronic component.
One way of establishing a temporary electrical connection between the test system and the contacts on the component employs a probe card carrying plurality of cantilevered wire probes. Such wire probes employ a relatively stiff wire tip at the end of an elongate arm. A plurality of these cantilevered wire probes are connected to a probe card and arranged in a predetermined array adapted for use with a specific microelectronic component configuration. The cantilevered wire probes may be attached to the probe card using an epoxy ring or the like. Alternatively, some commercially available systems employ exchangeable probes which allow each of the cantilevered wire probes to be removed from the probe card for repair or replacement.
Another common way to temporarily electrically connect a microelectronic component to a test system employs a probe card with rigid contacts. These contacts may be adapted to rigidly abut the component's contacts, e.g., a bond pad of an unbumped chip or wafer or solder balls on a bumped chip or wafer. These rigid contacts are arranged in an array which matches with the array of contacts on the microelectronic component to be tested.
When testing a microelectronic component with a conventional probe card (whether it be a cantilevered wire probe card, a rigid contact probe card, or another design), the probe card is positioned proximate the microelectronic component to be tested. The probe card and the microelectronic component are typically optically aligned with one another in an effort to precisely align each of the contacts or probes of the probe card with an electrical contact of the microelectronic component. The probes or the body of the probe card can interfere with a clear view of the microelectronic component contacts. As a result, it can be difficult to accurately align all of the test probes with the component contacts. The probes closest to the point(s) of visual alignment may be close to the target contact on the microelectronic component. Unfortunately, probes farther away from the point(s) of optical alignment can be displaced from their intended positions, leading to insufficient contact with some of the component contacts.
In some applications, it is necessary to test parametric contacts on a wafer with test probes to measure the quality of a semiconductor wafer at various stages of manufacture The parametric contacts are commonly positioned in “streets” between adjacent dies on the wafer. Some of the parametric contacts will be aligned along a street extending in an X-direction while other parametric contacts may be aligned along a street which extends in a generally perpendicular Y-direction. Testing these different sets of parametric contacts can be problematic because the arrangement of the dies and the contact may vary from one wafer to another. One approach used to address the variations in geometry from one wafer to another is to create a custom probe card for each wafer design. This can become fairly expensive, though, particularly for manufacturers that produce a number of specialty products in small runs. Another approach to address this problem employs a single probe card adapted for use with a single set of parametric contacts that are arranged along a single street or a single set of parallel streets. After the wafer is tested using this probe card, the wafer can be turned 90 degrees and the same probe card can be used to contact a second set of parametric contacts positioned in a perpendicular street. This may avoid the cost of manufacturing as many custom probe cards, but moving the wafer with respect to the probe cards and carefully realigning the probes with respect to the second set of parametric contacts is fairly time consuming, reducing throughput of the testing equipment.
For some applications, microelectronic components must be tested at different temperatures, such as in burn-in testing. When the microelectronic component under test changes temperature, it may expand or contract. The probe card and its associated probes may expand or contract at a rate which differs from the rate of expansion or contraction of the microelectronic component. As a consequence, many manufacturers must create two or more different probe cards for a single microelectronic component configuration, with each probe card being configured to accurately position the probes for contacting the component contacts at a particular temperature or narrow range of temperatures. Again, manufacturing multiple custom probe cards can be relatively expensive and can hamper efficient production of custom microelectronic components in small production runs.